Dutasteride in Treating Patients With Recurrent Prostate Cancer That Did Not Respond to Androgen-Deprivation Therapy

Inclusion criteria

DISEASE CHARACTERISTICS: * Diagnosis of prostate cancer * Asymptomatic progressive disease despite androgen-deprivation therapy * Progression must occur during androgen-deprivation therapy comprising orchiectomy or luteinizing hormone-releasing hormone (LHRH) analogue with or without antiandrogen AND after antiandrogen withdrawal * Concurrent LHRH monotherapy (i.e., LHRH analogs, such as leuprolide acetate or goserelin) required in patients who did not undergo prior bilateral orchiectomy to assure testicular androgen suppression * Recurrent disease, as indicated by at least 1 of the following: * Prostate-specific antigen (PSA) at baseline ≥ 2.0 ng/mL * Biopsy-confirmed local recurrence * Increase in size of measurable lesions on radiographic study * New lesion on a nuclear bone scan * Two successive increases in serum PSA measured at least 1 week apart PATIENT CHARACTERISTICS: * ECOG performance status 0-2 * Life expectancy ≥ 12 weeks * Platelet count ≥ 100,000/mm\^3 * Hemoglobin ≥ 9.0 g/dL * Bilirubin ≤ 2.0 mg/dL * SGOT ≤ 4 times upper limit of normal * Creatinine ≤ 2.0 mg/dL * Fertile patients must use effective contraception during and for 3 months after completion of study therapy PRIOR CONCURRENT THERAPY: * See Disease Characteristics * At least 28 days since prior radiotherapy and recovered * At least 28 days since prior flutamide OR at least 42 days since prior bicalutamide or nilutamide * Patients who have previously progressed despite antiandrogen withdrawal and who have started antiandrogens without reduction of serum PSA are eligible without requiring a 28- or 42-day washout interval after antiandrogen withdrawal * No other prior systemic therapies, except androgen-deprivation therapy (i.e., orchiectomy or LHRH analogues only) or antiandrogens * Surgery, brachytherapy, external-beam radiotherapy, and cryotherapy are not considered systemic therapies * No other concurrent anticancer therapy * No concurrent use of any of the following: * Finasteride * Other investigational 5α-reductase inhibitors * Anabolic steroids * Alpha-receptor blockers (e.g., indoramin, tamsulosin hydrochloride, prazosin, terazosin, alfuzosin hydrochloride, and doxazosin) * Drugs with antiandrogenic properties (e.g., spironolactone, flutamide, bicalutamide, cimetidine, ketoconazole, metronidazole, and progestational agents) * Products containing selenium ≥ 75 mcg or vitamin E ≥ 100 IU * Saw palmetto * EG6761 * No concurrent radiotherapy, including palliative radiotherapy for pain control